1. Field of the Invention
The present invention relates to a crankcase emission control system for use in an engine of an off-road vehicle. The present invention is especially suited for use in applications that can benefit from a crankcase emission control system that is easily attached, offers simple construction, and functions sufficiently even when the vehicle is operated when tilted in a horizontal or vertical direction.
2. Background Art
There are several conventional types of crankcase emission control systems. One crankcase emission control system utilizes an air cleaner and a reduction chamber that is heated by the hot exhaust gases passing through the muffler. This type of system is shown in Japanese Patent Laid-open No. Hei. 11-036841. A second type of crankcase emission control system is shown in Japanese Patent Laid-open No. Hei. 10-212923, where lubrication oil is returned to the engine case via a breather hose arranged in an elevated position above a crankcase. A third type of crankcase emission control system is shown in Japanese Patent Laid-open No. Hei. 11-50831. This system includes a gas-liquid separation chamber provided with an oil removing means to separate crankcase lubricant from gas emissions.
However, with each of the above-described conventional examples, reduction is carried out in combination with an air cleaner. This can have a considerable effect on the intake air amount of the air cleaner. In addition, since special components are required for attachment of the conventional devices, the overall number of components is increased. Finally, if the posture of a vehicle changes severely, such as when the vehicle is being driven off-road, a liquid component of the blow-by gas is likely to flow directly to an air cleaner side of these systems. Similarly, when a 4-wheeled buggy is stored in an upright position, a liquid component inside the gas-liquid separation chamber is also likely to flow to the air cleaner side of these systems.